Generally, a buoyancy compensator jacket enables the diver to take his/her position underwater at the desired depth and acts as a structure transporting one or more cylinders for an air or gas mixture.
To this end, the buoyancy compensator jacket comprises:
an airtight bladder or casing equipped with a system for connection to the body;
a system for inflating the bladder that is manually operable and usually supplied with the compressed gas of the cylinder;
a system for draining the inflation gas of the bladder, in turn comprising one or more vent valves that are manually operable and optionally one or more valves for automatically venting the gas;
a frame fastening one or more cylinders of an air or other breathing gas mixture.
Briefly, the regulation of the amount of gas contained in the bladder allows the diver's body to be positioned and stabilized in water at different depths; its operation and possible equipment are however generally known to the person skilled in the art and, therefore, no additional reference is made thereto.
The system for connecting the airtight bladder to the diver's body usually comprises a backplate, generally rigid, and a harness, in turn having shoulder strap elements, and a ventral belt or strap (or securing strap) at the waist with removable closure elements, such as buckles or the like.
The cylinder in turn is connected to the backplate by one or more belts or the like.
More in details, a known embodiment (possibly one of the most conventional ones) of a buoyancy compensator jacket includes a vest or waistcoat that houses or forms the inflatable bladder or casing. The jacket is worn and secured on the user's torso by a pair of shoulder straps or strips and has at least one ventral belt or strap (or securing strap) at the waist.
The backplate can be fastened to the back region of the jacket in different manners.
The ventral belt or strap can be fastened to the jacket or preferably to the backplate.
Therefore, while in the ventral region there is a substantially direct coupling between the backplate, to which the cylinder is connected and the ventral belt or strap element, thereby the backplate and so the cylinder are firmly held against the diver's body, in the upper part of the backplate, with reference to the upright position of the user, the connection of the backplate with the diver's body is indirect since it occurs through shoulder straps that support the weight thereof with the jacket in the worn condition, as the shoulder straps are an extension of the bladder, and the bladder, as a waistcoat, being connected to the backplate; it has to be noted—parenthetically—that also the ventral strap or belt can be connected to the bladder and not directly to the backplate.
At most in the sternal region of the user it is possible to provide a brace that removably connects the shoulder straps with each other and that prevents them from progressively opening wide. Such brace however does not give any effect for fastening the backplate to the user body in the area of the sternal strap or chest of the user.
Such configuration of the jacket has some limits particularly as regards a firm fastening of the cylinder to the body, that is to the back of the user. When the user transports the cylinder in water and above all on ground, the cylinder that is the most heavy element of the assembly and therefore affecting his/her stability, is coupled by the backplate in an indirect manner to the top part of the diver's body (through the shoulder straps, that are an extension of the inflatable bladder) and therefore a certain degree of relative movement is possible between the cylinder and the diver in the form of a kind of lateral displacement or lateral swinging. Such effect is found both in jackets as the one described above and in jackets where the shoulder straps, and the waist securing strap or belt, are directly coupled to the backplate.
Moreover the shoulder straps are not particularly comfortable for the diver, since the weight and the movement of the cylinder, when getting dressed or when diving, create a certain compression and a certain friction, particularly at the shoulders and the chest, where the weight of the cylinder is discharged on the diver's body.
The conceivable consequences of the possible relative movements between the backplate and the diver are not limited to discomforts for the user—that with no wet suit can cause even injuries—but are extended also to possible early deteriorations or damages of the wet suit and/or of the jacket.
Such drawback is more present if the diver is a woman: in this case the pressure on the chest is exerted on the immediate vicinity of the breast, a particularly sensitive and delicate area.
Jackets for women are known in prior art that provide arrangements to improve wearability. In the case of the patent n. U.S. Pat. No. 5,662,433 it describes a jacket with improved wearability above all suitable for women, wherein each shoulder strap element is connected to the ventral belt or strap by a triangular shaped element, composed of a framework made of a more resistant material that surrounds a central portion made of elastic material.
This pair of triangular shaped elements, in combination with the shoulder straps and the ventral strap should allow the weight to be better distributed on shoulders, waist and hips of the diver, limiting the discomfort caused by buckles and by belts at the breast.
Although generally it is functional, however such solution has some limits.
Firstly, the triangular shaped elements are part of the structure of the shoulder strap and connect it to the ventral part, therefore the shoulder straps are also involved in supporting the weight of the cylinder and transmit a tensile force through the jacket and the triangular shaped elements, from the backplate to the ventral strap or belt; it results that inevitably the triangular shaped elements exert a certain effect pressing the chest that is perceptible by the diver, even if at a less extent than conventional jackets.
Moreover the solution with the triangular shaped elements connected to the shoulder straps does not result in a better fastening of the backplate to the sternal part of the user compared to that provided by the shoulder straps.
Another known solution, for some aspects similar, is disclosed in the patent U.S. Pat. No. 5,902,073 showing a jacket with a vest that can be divided into two parts, left and right, each one fastenable to the respective shoulder strap.
The limits of such solution, within such sphere, are substantially equal to the ones described above and therefore no further reference is made thereto.